Twin offspring born to ewes fed a diet that provided 52% of the recommended energy intake for a pregnant ewe during the last trimester of gestation were lighter at birth (3.58 vs. 4.32 kg), had smaller adrenal glands (674 vs. 893 mg) and had smaller livers (72.39 vs. 126.63 g) than twin offspring born to ewes fed a diet that provided 100% of the recommended energy intake. Growth hormone levels were high at surgery (115-120 days of gestation) in both ewes (33 to 65 ng/ml) and fetuses (180 to 350 ng/ml). Following surgery, levels in ewes decreased to between 2 and 12 ng/ml until just prior to parturition when the levels again increased. Fetal levels ranged from 100 to 200 ng/ml from surgery until about 10 days prior to parturition. At this time, levels in twin fetuses of low-energy ewes increased to 197 to 262 ng/ml while levels in twin fetuses of high-energy ewes ranged from 100 to 144 ng/ml. Maternal and fetal levels of triiodothyronine ranged from 0.5 to 3.5 ng/ml and did not appear to be influenced by surgery, diet, or parturition.